With the rapid development of communications technologies, a high speed, a large capacity, and wide coverage have become main features of a modern communications system. A MIMO (multi-input multi-output) technology, by using resources in a spatial dimension, allows a signal to obtain an array gain, a multiplexing gain, a diversity gain, and an interference cancellation gain in space, so that a capacity and spectral efficiency of the communications system are exponentially increased. An LTE (Long Term Evolution) system can support, at a transmit end and a receive end, transmission of data streams at up to eight layers by using a multiple-antenna system. However, the modern communications system will face challenges of a larger capacity, wider coverage, and a higher rate, and the receive end and the transmit end have a larger quantity of antennas, that is, a high dimensional MIMO (High Dimensional MIMO, HD-MIMO) system will be a key technology for resolving the problem. However, in an HD-MIMO scenario and a high-order (SU-HD-MIMO) communications system, when a quantity of antenna dimensions is extremely high, DMRSs (demodulation reference signals) at eight layers corresponding to data streams at eight layers are far from enough. Because of a limit of an antenna scale, an antenna scale (8T8R) involved in an existing standard and a patent, and a corresponding DMRS design scheme all support data transmission of less than eight streams. For example, on a resource block (RB), mutually orthogonal DMRS signals at a maximum of eight layers are multiplexed. A DMRS signal is used to demodulate a PDSCH (physical downlink shared channel), and the DMRS signal is generally used to support a beamforming technology and a precoding technology. Therefore, the DMRS signal is only transmitted on a scheduled resource block, and a quantity of transmitted DMRS signals is related to a quantity of data streams (sometimes also called a quantity of layers), and the transmitted DMRS signals are in a one-to-one correspondence with antenna ports. Compared with an 8T8R MIMO system, the high dimensional MIMO system more easily enables a system to implement high-rank (Rank>8) data transmission, and further improve a throughput of an SU-MIMO system.
In conclusion, it is necessary to put forward a new resource allocation method and apparatus. That is, on the premise of existing DMRS pilot overheads, an orthogonal DMRS design method for up to 24 data streams is implemented by means of new port mapping.